powerpc/mpc85xx: SECURE BOOT- Add secure boot target for P5040DS

Secure boot target is added for P5040DS platform.
Signed-off-by: NGaurav Rana <gaurav.rana@freescale.com>
Reviewed-by: NYork Sun <yorksun@freescale.com>

board/freescale/corenet_ds/MAINTAINERS

@@ -27,3 +27,4 @@ F:	configs/P5040DS_defconfig
 F:	configs/P5040DS_NAND_defconfig
 F:	configs/P5040DS_SDCARD_defconfig
 F:	configs/P5040DS_SPIFLASH_defconfig
+F:	configs/P5040DS_SECURE_BOOT_defconfig

configs/P5040DS_SECURE_BOOT_defconfig

+CONFIG_SYS_EXTRA_OPTIONS="SECURE_BOOT"
+CONFIG_PPC=y
+CONFIG_MPC85xx=y
+CONFIG_TARGET_P5040DS=y